(a) Field of the Invention
The present invention relates to an apparatus and method for reducing power consumption of a communication device using batteries to extend the operating time of the device. More specifically, the present invention relates to an apparatus and method for reducing power consumption by controlling the efficient switching of operation between active and passive communication devices.
(b) Description of the Related Art
Power saving is of great importance in various devices, including communication devices such as mobile communication terminals, mobile Internet terminals, WPAN (Wireless Personal Area Net) terminals, and sensor network nodes.
The communication device, with the power on, stays in the idle stat most of the time. In the idle state, the communication device periodically receives broadcasting information from a base station, an access point, or a coordinator, and updates the related information.
The communication device also receives paging information from the coordinator to compare a received ID with its own, and if the received ID matches its own, performs a paging response procedure. With a change in the location as the terminal travels, the communication device registers the changed location on the coordinator.
In this manner, the periodic operation of the terminal in the idle state results in power consumption caused by a state transition of the communication device, and data transmission/reception, and hence reduces the operating time of the terminal.
In a conventional method, a passive signal discriminator for wake-up of a low-voltage responsor has a structure that prevents unnecessary wake-up of the low-voltage responsor caused by noise signals generated from a television or a monitor.
In this method, the low-voltage responsor is provided with an additional low-pass filter having a specific threshold value, so as to decrease the number of unnecessary wake-ups caused by noise and reduce power consumption of the low-voltage responsor efficiently. Furthermore, since the passive low-pass filter does not consume battery power, it actually reduces unnecessary power consumption.
This method is useful in the case where the coordinator and the terminal exist in one-to-one correspondence and their communication procedure is extremely simple. But, it is ineffective when multiple terminals are present in one area and the related communication procedure is complicated, as in the mobile communication environment.
In another conventional method, the paging integration dynamic power management method, the state to which the communication device can transit is divided into several steps, and the communication device is transited to a deep idle state to acquire a power gain greater than the power consumption caused by the state transition, the corresponding state being maintained for a sufficient time period. Thus the power consumption caused by frequent state transitions can be reduced. The communication device includes a passive receiver and a decoding logic in addition to basic communication devices, to perform reception and comparison of group paging codes with the passive receiver and the decoding logic.
In this method where the paging unit comprises group units, however, the terminal which wants to check paging information for itself is required to receive a paging list through an active communication device and to check whether or not its ID is in the paging list.
Most of all, when the passive receiver of the terminal is located in the environment (e.g., the shadow area not suitable for the reception of the power transmit signal of the coordinator) that does not support a normal operation of the passive receiver, the conventional methods do not provide a means for checking whether the paging information of the coordinator is successfully received. Additionally, the periodically received broadcasting information of the coordinator cannot be processed, resulting in difficulty in actively performing the mutual operations between the active and passive communication devices.